Apparatus for pulping and grading of waste paper

ABSTRACT

A receptacle accommodates a waste paper suspension and a rotor located adjacent one portion of the receptacle wall. A first outlet is provided in the wall in the region of the rotor so that pulp produced by shredding of waste paper by the rotor can be discharged from the receptacle. A strainer is interposed in the first outlet, and a second outlet is provided in an opposite portion of the wall and arranged to discharge matter having low specific gravity from the receptacle.

This is a continuation of application Ser. No. 487,273 filed July 10,1974, now abandoned, which, in turn, is a continuation of applicationSer. No. 275,830 filed July 27, 1972, now U.S. Pat. No. 3,844,488.

BACKGROUND OF THE INVENTION

The present invention relates to the preparation of waste paper stock ingeneral, and more particularly to an apparatus for pulping and gradingof waste paper to thereby produce a waste paper stock therefrom.

The recovery of pulp or stock from waste paper is well known per se. Itis known that for this purpose the waste paper must be shredded in asuspension, to form from it a pulp which can be further processed. Adifficulty in the preparation of stock from waste paper resides in thefact that quite often substances of low specific gravity, such assynthetic plastic foams, rubber, foils and the like are contained in thewaste paper, substances which can be removed from the receptacle whereinthe pulping takes place neither through the pulp outlet nor through theoutlet provided for removal of heavy substances which are not intendedto be used as part of the pulp. The difficulties created by thislight-weight, hereafter designated for the sake of convenience as"impurities", result from the fact that such matter accumulates veryrapidly in the receptacle so that after an operating period of only afew days the apparatus must be shut down to permit a complete emptyingof the receptacle. It has been observed that in many instances theoperating time of the apparatus, that is the time from one to the nextshut-down and complete emptying of the receptacle of the apparatus, isas little as two or three consecutive days.

It goes without saying that a complete shutdown of the apparatus meanslost time and increased expenses, and that this is not tolerable. Theproblem having been realized, the prior art has proposed to withdrawfrom the receptacle a partial stream of the pulped suspension, to supplyit to an additional pulper or disintegrator and to a subsequent coarsegrading device, and then to return it into the original receptacle. Suchan approach does offer some hope of improvement, but quite evidently italso will increase the expenses involved and decrease the economy ofoperation of an apparatus of the type here under discussion, due to theinvestment costs required for the additional equipment and the increasedenergy requirements for operating such equipment. The problem outlinedabove thus has not heretofore been satisfactorily solved.

SUMMARY OF THE INVENTION

It is, accordingly, a general object of the present invention to providean improved apparatus for pulping and grading of waste paper, which isnot possessed of the disadvantages outlined above with respect to theprior art.

More particularly, it is an object of the present invention to providesuch an apparatus which assures the longest possible operating periodbefore complete emptying of the apparatus becomes necessary.

An additional object of the invention is to provide such an apparatuswhich is simple in its construction and reliable in its operation.

In pursuance of these objects and of others which will become apparenthereafter, one feature of the invention resides, in an apparatus forpulping and grading of waste paper, in the provision of a combinationwhich comprises a receptacle adapted to accommodate a waste papersuspension and having a peripheral wall, and rotor means located in saidreceptacle adjacent one portion of said wall and being operative forshredding said waste paper in said suspension so as to obtain a pulp.First outlet means is provided in the wall in the region of the rotorfor discharge of the pulp from the receptacle, and strainer means isprovided for straining the pulp which is discharged through the firstoutlet means. In accordance with the invention there is further providedsecond discharge means, in another portion of the wall which is oppositethe one portion and the rotor means and this second discharge meansserves for discharging from the receptacle of matter having low specificgravity.

It has been found that the flow of suspension which is caused in thereceptacle by the operation of the rotor causes an accumulation of thelow specific gravity matter, that is the light-weight matter, in theregion of the aforementioned other wall portion. If the second dischargemeans is provided in this region, then the accumulating light-weightmatter or "impurities" will flow out through this second dischargemeans. It is advantageous to normally keep the second discharge meansclosed in order to avoid significant losses of desirable pulp matter,and to open it only briefly from time to time to permit the discharge ofaccumulated impurities.

It has been found that in an apparatus according to the presentinvention it is possible to operate the apparatus continuously forperiods of several weeks before it becomes necessary to shut theapparatus down in order to empty it out completely.

According to a further concept of the invention it may be advantageousto connect the second discharge means with a suction arrangement, forinstance a pump or a gravity tube, to assure that the impurities can bereadily discharged from the receptacle in a simple and reliable mannereven if the receptacle is of the open type, that is not of the typewhich is under internal overpressure.

The receptacle may further be provided in an inner surface of itsperipheral wall with an annular recess which is coaxial with the axis ofrotation of the rotor. In such a recess the heavy fraction of the wastepaper will settle, and can then be removed by means of an appropriateoutlet communicating with this recess. In such a construction bothundesirable fractions, namely the light-weight impurities and theheavy-weight matter can be removed without any difficulties so that onlythe desirable pulp will be recovered for further use.

The rotor itself may be of such construction that the vortex flowcreated in the suspension by rotation of the rotor, and which extendscoaxial with the axis of rotation of the rotor, will have a vortex corewhich extends from the rotor to the opposite wall portion of thereceptacle, that is the wall portion in which the discharge means forthe impurities is located. In such a construction, the vortex core isessentially centered in the receptacle and the region where thedischarge for the impurities must be provided, can thus be determinedprecisely.

It is particularly advantageous if upstream of the receptacle there islocated an additional unit also having a receptacle adapted toaccommodate a waste paper suspension and being in its arrangement andits associated components -- namely the rotor means, the first outletmeans and the strainer means -- essentially similar to the apparatusalready outlined. The outlet for the pulp which issues from theadditional receptacle then communicates with an inlet of thefirst-mentioned receptacle, and the strainer means should be coarserthan that of the first-mentioned receptacle.

In place of the second discharge means for light-weight impurities, thesecond receptacle is provided in the wall portion opposite its rotorwith an outlet through which tangled suspension components can bewithdrawn in form of elongated rope-like wads. With such an apparatusall undesirable contaminants accommodated in or forming part of thewaste paper can be largely removed, thus assuring the production of ahigh-grade pulp having a minimum of contaminants, and at the same timeassuring a maximum length of continuous operation without downtime. Theenergy required for operating the first-mentioned receptacle with itsassociated components, that is the receptacle having the seconddischarge means for the light-weight impurities, is relatively small,because the rotor of this second receptacle or downstream receptaclewill be required only for additional shredding of the waste paper whichhas already received its initial shredding in the upstream receptacle.and the desired low providing for the discharge of the light-weightimpurities through the second discharge means is produced as a highlydesirable incidental effect requiring no additional energy. The novelfeatures which are considered characteristic for the invention are setforth in particular in the appended claims. The invention itself,however, both as to its construction and its method of operation,together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view illustrating one embodiment of theinvention;

FIG. 2 is a diagrammatic vertical section through another embodiment ofthe invention; and

FIG. 3 is a diagrammatic vertical section through still an additionalembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Discussing now forstly FIG. 1 of the drawing it will be seen that inthis embodiment there is provided an apparatus 1 in accordance with thepresent invention. This apparatus 1 is a part of a waste paper stockpreparation plant the details of which are not illustrated because theydo not form a part of the invention and are known per se. What is novelin accordance with the present invention is the apparatus 1, a pulperand grader for waste paper. The apparatus 1 has a receptacle or housing2 which in the illustrated embodiment is substantially cylindrical inits configuration and is a closed housing. Its axis of symmetry ishorizontal in this embodiment.

The housing 2 has a peripheral wall which is provided, in the region ofone axial end of the receptacle 2, with a supply conduit 3 which enterssubstantially tangentially and supplies into the housing 2 a suspensionof waste paper and a liquid, usually water. A drive shaft 5 extends intothe housing through the opposite axial end wall thereof, the drive shaft5 being adapted to be driven in rotation by a non-illustrated motivesource, Mounted at or on the inner end portion of the drive shaft 5 is arotor 6 which is itself of known construction, and, when rotated byrotation of the drive shaft 5 shreds the waste paper in the suspensionin the interior of the housing 2 and forces the thus obtained pulpthrough a screen 7 and subsequently into a collecting chamber 8 fromwhich the pulp enters into an outlet 9. The circumferential wall of thehousing 2 is provided in this embodiment with an annular recess 10 withwhich an outlet 11 communicates.

The axial end of the housing 2 which is opposite that end at which therotor 6 is located, is provided with an outlet 4, and in the illustratedembodiment the axis of rotation of the rotor 6 and the longitudinal axisof the outlet 4 are coincident.

Rotation of the rotor 6 causes in the suspension accommodated in thehousing 2 a flow pattern which is indicated by the arrows of FIG. 1. Itis clear that the suspension entering into the housing 2 from thetangentially discharging inlet conduit 3 is given a flow direction inthe region of the end wall where the inlet 3 discharges, which causes itto flow in axial direction longitudinally of the axis of rotation of therotor 6 and towards the latter. The pulp or stock which results fromshredding of the waste paper in the suspension by the rotor 6 is forcedby the rotor through the screen or strainer 7 to subsequently enter theoutlet 9. Those suspension components which have not been sufficientlyshredded to pass through the strainer 7 flow substantially along thecircumferential wall of the housing 2 back to the end wall in the regionof which the inlet 3 discharges the newly incoming suspension.

heavy suspension components, for instance metallic contaminants in thesuspension, will settle in the recess 10. light-weight components orimpurities, for instance synthetic plastic foam, rubber or the like,accumulate in the region of the end wall provided with the outlet 4 andleave the housing 2 through the latter. Advantageously the outlet 4 isprovided with a closing device, for instance a known valve or the like,not shown, which normally closes the outlet 4 and which is opened onlyfrom time to time to permit the removal of accumulated light-weightcontaminants or impurities without resulting in the loss of asubstantial amount of pulp or useable waste paper.

It will be understood that the rotation of the rotor 6 causes a vortexflow which extends axially along the axis of rotation of the rotor 6 tothe end wall provided with the outlet 4. The flow has a vortex corecentered on the one hand by the construction of the rotor 6 and on theother hand by the housing wall, so that the location for the outlet 4can be precisely determined in conjunction with the readily calculablemanner in which the light-weight impurities will be ejected from thevortex core.

In FIG. 2 I have illustrated an embodiment which is quite similar tothat of FIG. 1 except that the housing 2' is open, rather than closed asthe housing 2 in FIG. 1. In FIG. 2, components similar to those of FIG.1, have been given the same reference numerals but with a prime suffix.A conduit 18 communicates with that end wall of the housing 2' which isaxially spaced from the rotor 6', the latter being mounted on the driveshaft 5' which here is shown as being connected with the drive means 5",the latter being diagrammatically illustrated and representative of anelectric motor or the like.

The purpose of the conduit 18 is to permit the withdrawal of rope-likewads 29 of tangling components of the suspension. The formation of suchwads is well known and they can be withdrawn by means of the withdrawalrollers 30, 30 shown in FIG. 2, one or both of which may be driven forthis purpose.

An outlet conduit 4', corresponding to the outlet 4 of FIg. 1,communicates with the conduit 18 for the withdrawal of the light-weightimpurities from the interior of the housing 2'. In the embodiment ofFIg. 2, the conduit 4' has interposed in it a suction means, hereillustrated in form of pump P. although it is possible to replace thepump P by constructing the outlet conduit 4' itself as a gravity tube inwhich suction is created by the gravity descent of matter in the tube.The outlet 11' is here provided with a slide valve 11" for controllingthe outflow of matter.

Reference numeral 23 designates in this embodiment a bail of waste paperto be shredded and reference numeral 24 designates an inlet conduit forliquid.

FIG. 3, finally, illustrates still a further embodiment of theinvention. Here, there is provided an apparatus 1 which is essentiallythe same as that shown in FIG. 1, but which operates in conjunction withan apparatus 21 resembling essentially (but with some modifications) theapparatus of FIG. 2. In particular, like components are identified withlike reference numerals as in the preceding embodiments to the extentpossible without producing confusion.

In FIG. 3 the apparatus 21 has a housing 22 or a receptacle, which isopen at the top, and into which unless 23 of waste paper to be pulpedare introduced. Reference numeral 24 designates an inlet conduit foradmission of liquid in which the paper is to be suspended.

One side wall of the housing 22 has a drive shaft 25 of a drive 25'passing therethrough, carrying at the inner end located within thehousing 22 a rotor 26 which may be similar to the one shown in FIG. 1.The rotor 26 again serves for shredding of the waste paper whichcirculates in suspension in the housing 22, and for forcing the shreddedwaste paper in form of pulp through the screen 27 into the chamber 33from where it passes into the inlet conduit 3 of the housing 2 of theapparatus 1 which is located downstream with respect to the apparatus21. Clearly it is not necessary that the apparatus 1 be locatedphysically at a lower lever than the apparatus 21 but it must be kept inmind that the apparatus 1 is to be located downstream of the apparatus21, that is it must receive pulp from the latter.

The wall of the housing 22 which is located oppositely to and spacedfrom the rotor 26 is provided with a conduit 28 whose purpose is thesame as the conduit 18 in FIG. 2, namely to permit withdrawal of arope-like wad 29 of tangling matter which is part of the bales 23 ofincoming waste paper. The wad 29 is withdrawn by the withdrawingarrangement 30 which is the same as that in FIG. 2.

The bottom wall of the housing 22 is provided with an outlet conduit 31through which heavy fractions of the suspension, for instance, metallicparts or the like, can be withdrawn after settling at the bottom. Theoutflow of matter through the outlet conduit 31 is controlled by a slidevalve 32 which is operated by a diagrammatically illustratedarrangement, and which is opened from time to time to permit theissuance of the accumulated heavy matter.

The apparatus 1 is essentially the same as that illustrated in FIG. 1,except that as shown in FIG. 3, the apparatus 1 is turned end for endwith respect to the showing in FIG. 1. It is emphasized that althoughthe housing 2 of the apparatus 1 in FIG. 3 is closed, as is the case inFIG. 1 also, the housing could be open as is the housing 22 of theapparatus 21. The screen 27 is coarser -- that is of larger mesh -- thanthe screen 7 of the apparatus 1 so that pre-pulping takes place in theapparatus 21 and final pulping in the apparatus 1. As in the embodimentof FIG. 1, the flow is illustrated with the arrows in the housing 2 ofthe apparatus 1 and it will be seen that the impurities oflight-specific gravity are shown as tending to accumulate in the regionof the axial end wall which is remote from the rotor 6, that is in theregion where the outlet 4 is provided. In FIG. 3 I have shown that theoutlet 4 can be normally closed by means of a slide valve 4" and can beopened from time to time to permit withdrawal of the accumulatedlight-weight impurities, for instance by means of the diagrammaticallyillustrated pump P. Maintaining the outlet 4 normally closed preventsthe loss of desirable matter, that is of pulp or the like. Thecircumferential recess 10 resembles the one illustrated in FIG. 1 and isprovided for the same purpose. Its outlet 11' is closed by a slide valve11", which is normally closed and can be opened from time to time topermit the removal of accumulated heavy matter. The control of themovements of the slide valves 4" and 11' is effected by thediagrammatically illustrated devices which do not form a part of theinvention and require no further detailed discussion.

Due to the fact that the mesh size of the screen or strainer 27 of theapparatus 21 is relatively large, between substantially 14 and 25 mm.with respect to substantially 4-14 mm. for the screen 7 of theapparatus 1. the light-weight impurities can leave the apparatus 21together with the pulp. This prevents the light-weight impurities fromblocking the apparatus 21 after a relatively short period of operation.The tangling components, however, are almost completely removed to formof the wad 29 so that the suspension as it enters the apparatus 1contains almost no such components. On the other hand, the light-weightimpurities are almost completely removed in the apparatus 1, so thatthey cannot accumulate therein and do not necessitate the shutting-downof the apparatus except after periods of operation which may last aslong as several weeks.

With the embodiment in FIG. 3, the volumetric content of the housing 2of the apparatus 1 can be substantially smaller than that of the housing22 of the apparatus 21. Practical tests have shown that a size ratio of10:1 for the apparatus 21 versus the apparatus 1 is possible, and it hasbeen determined that a volumetric content of between 20-40 m³ for theapparatus 21 and of about 3.5 m³ for the apparatus 1 are advantageous.

It will be seen that with the present invention the difficulties of theprior art have been overcome and the objects outlined herein have beenattained. It is now possible to operate an apparatus according to thepresent invention for periods of several weeks without having to shut itdown in order to remove accumulated light-weight impurities from thehousing or receptacle. Evidently, this not only results in a saving indown-time, but also in a generally more economic operation of theapparatus.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in anapparatus for pulping and grading of waste paper, it is not intended tobe limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention andtherefore, such adaptations should and are intended to be comprehendedwithin the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. In an apparatus for the comminutionand grading of waste material, particularly for the pulping and gradingof waste paper, a combination comprising at least the closed pressurizedreceptacle for receiving a waste material suspension, said receptaclehaving wall means including a peripheral wall and two oppositely locatedend walls; rotor means located in said receptacle adjacent one of saidend walls for comminuting the waste material in said suspension so as toobtain a stock component, an impurity component of low specific gravitywhich is in the form of a suspension and an impurity component of highspecific gravity; first outlet means provided in said wall means in theregion of said rotor means for discharge of said stock component fromsaid receptacle; strainer means for straining of the stock componentdischarged through said first outlet means; second outlet means providedin the other of said end walls for discharge from said receptacle ofsaid impurity component of low specific of low specific gravity; meansfor regulating the discharge of said impurity component of low specificgravity through said second outlet means; and third outlet meansprovided in said wall means for discharge from said receptacle of saidimpurity component of high specific gravity.
 2. A combintion as definedin claim 1, wherein said first and second outlet means each include anoutlet duct.
 3. A combination as defined in claim 1, wherein saidregulating means comprises valve means.
 4. A combination as defined inclaim 1, wherein saiid regulating means comprises pump means.
 5. Acombination as defined in claim 1, and further comprising a recess insaid wall means for accumulation of said impurity component of highspecific gravity.
 6. A combination as defined in claim 5, said rotormeans including a rotor which is rotatable about an axis of rotation;and wherein said recess is of substantially annular configuration and issubstantially coaxially arranged with said rotor.
 7. A combination asdefined in claim 1; and further comprising discharging means connectedwith said second outlet means.
 8. A combination as defined in claim 7,wherein said discharging means comprises a gravity tube.
 9. Acombination as defined in claim 7, wherein said discharging meanscomprises suction means.
 10. A combination as defined in claim 1, saidrotor means including a rotor which is rotatable about an axis ofrotation; and wherein said second outlet means is located substantiallyon a direct line with said axis of rotation.
 11. A combination asdefined in claim 1, said rotor means creating in said suspension avortex flow having a core region; and wherein said other end wallextends across said core region.
 12. A combination as defined in claim11, wherein said rotor means and said other end wall are arranged sothat said vortex flow extends to said other end wall.
 13. A combinationas defined in claim 11, said rotor means including a rotor which isrotatable about an axis of rotation, and said core region extendingaxially of said rotor; and wherein said second outlet means and saidcore region at least partially overlap one another.
 14. A combination asdefined in claim 1; and further comprising additional regulating meansfor regulating the discharge of said impurity component of high specificgravity from said receptacle.
 15. A combination as defined in claim 1,wherein said receptacle is of closed construction so as to permit thedevelopment of an internal overpressure in said receptacle.
 16. Acombination as defined in claim 1; further comprising an additionalreceptacle connected in series with said one receptacle, said additionalreceptacle having an inlet for said waste material; and at least onerotatable member in said additional receptacle for comminuting saidwaste material, said rotatable member initially comminuting said wastematerial and said rotor means further comminuting said waste material.17. A combination as defined in claim 16; and further comprising atleast one strainer for straining the initially comminuted waste materialprior to further comminution thereof by said rotor means.
 18. Acombination as defined in claim 17, wherein said one strainer is ofcoarser mesh than said strainer means.
 19. A combination as defined inclaim 16, said rotatable member causing the formation of at least oneelongated rope-like wad during the initial comminution of waste; andfurther comprising additional outlet means in said additional receptaclefor withdrawal of said wad from the latter.
 20. A combination as definedin claim 19; and further comprising withdrawing means for withdrawingsaid wad from said additional receptacle.
 21. A combination as definedin claim 19, said additional receptacle having additional wall meansincluding an additional peripheral wall and two oppositely locatedadditional end walls; and wherein said rotatable member is arrangedadjacent one of said additional end walls and said additional outletmeans is provided in the other of said additional end walls.
 22. Acombination as defined in claim 16, wherein additional outlet means fordischarge of the initially comminuted waste material from saidadditional receptacle is provided in the latter in the region of saidrotatable member.
 23. A combination as defined in claim 16, wherein aninitial impurity component of high specific gravity is obtained duringthe initial comminution of said waste material; and further comprisingadditional outlet means in said receptacle for discharge of said initialimpurity component from the latter.
 24. A combination as defined inclaim 23; and further comprising additional regulating means forregulating the discharge of said initial impurity component from saidadditional receptacle.